Lubricant compositions



LUEREQANT COMPOSITIONS Warren Lowe, Berkeley, Calif., assignor toCalifornia Research Corporation, San Francisco, Calif., a corporation ofDelaware No Drawing. Application June 29, 1954, Serial No. 440,280

3 Claims. (Cl. 252-491 This invention relates to novel lubricantcompositions. More particularly, the invention is concerned with novellubricating oil compositions having improved oxidation and corrosioninhibiting properties.

Lubricating oils generally have a tendency to deteriorate due tooxidation and form decomposition products which are corrosive to metals.Since lubricating oils in use today almost invariably come into contactwith metal surfaces, the problem of overcoming oxidation and corrosionis considered to be one of major importance. Operating conditionsencountered in modern internal combustion engines in which these oilsare commonly employed involve increased temperatures, higher speeds andreduced clearances which tend to promote decomposition and the formationof corrosive products. Furthermore, these engines generally employ alloymetal bearings which, besides their possible catalytic eifect on thedecomposition of the hydrocarbon type mineral lubricating oils, areeasily corroded and this, in turn, has seriously accentuated theoxidation and corrosion problems in mineral lubricating oils.

Inhibitors have been added to lubricating oils to improve theirresistance to decomposition and avoid corrosivity. Mineral lubricatingoils for internal combustion engines, due to the severity of theirservice, have also been compounded with additional agents such as Wearinhibitors, sludge inhibitors and detergents to loosen and suspendproducts of decomposition and counteract their effect. Unfortunately,many of these agents may adversely affect the eificiency of theoxidation and corrosion inhibitors and it is a problem to findinhibitors Which will function in combination wth them. Furthermore,some of the most eifectve oxidationand corrosion inhibitors containactive sulfur and are, therefore, ex-

tremely corrosive to silver and similar metals which are subject toattack by active sulfur. These types of metals, although once not soWidely used in contact with lubricating oils and therefore considered toconstitute only a minor problem, are being increasingly employed today.Particularly in certain important classes of internal combustion enginesas, for example, marine and railroad diesel engines, silvermetal-containing bearings are more and more common and the problem ofproviding proper lubrication for them is one' of major importance.

It is, therefore, a general object of this invention to providelubricating oil compositions having improved antioxidant andanticorrosion properties.

A more particular object of the invention is to provide lubricating oilcompositions Which are noncorrosive to silver and similar metals.

Another more particular object is the provision of mineral lubricatingoil compositions in which the tendency to corrode alloy bearings ofinternal combustion engines has been inhibited. V

A further and somewhat related object is 'to' provide compounded minerallubricating oil compositions-having improved anticorrosion propertieswithout adversely afice - 2 fecting the stabilizing, deterging andlubricating qualities of the hydrocarbon oil composition.

Another and still more particular object of the invention is theprovision of mineral lubricating oil compositions which are noncorrosiveto silver metal-containing bearings of the type employed in railroaddiesel engines.

Additional objects of the invention will become apparent from thedescription and claims which follow.

In the accomplishment of the above objects, it has been found thatcompositions comprising an oil of lubricating viscosity and a complex oftitanic acid with a member of the group consisting of glycols andpolyhydroxy benzenes have greatly enhanced anticorrosion properties. Ithas also been found that, in particular, compositions comprising acompounded mineral lubricating oil for internal combustion engines whichis normally corrosive to alloy bearings and such a complex aresubstantially noncorrosive.

The normal tendency of oils to become oxidized and corrosive isdefinitely inhibited in the improved compositions of the invention.Metal surfaces in general are not corroded by contact with thesecompositions and internal combustion engine alloy bearings, inparticular, are remarkably benefited. Bearings of silver and similarmetals which, as stated above, are increasingly important due to theirpresently expanded use in marine and railroad diesel engines, are notcorroded by these compositions whereas conventional oxidation inhibited'oils have severely pitted and corroded such bearings. The ad-' vantagesof these improvements are obtained in the compositions of this inventionwithout loss of stability or detergency in the composition.

The titanic acid complexes of the compositions according to thisinvention are prepared by the reaction of a mixture of a reactivetitanic acid derivative, such as the titanium tetrahalides or titaniumtetra-alkyl esters. and glycol or polyhydroxy benzene. The mixtures areordinarily heated to accelerate the reaction. Although the nature of thereaction is not definitely known, it is believedthat two of the hydroxylgroups of a single glycol or polyhydroxy benzene react with the titanicacid derivative to form What is commonly termed a metal chelatecompound. These compounds are characterized by a claw type of structurein which one or more rings of similar or unlike structure due to the useof mixed glycols or polyhydroxy benzenes are formed including thetitamum.

The glycols which are reacted with the titanic acid derivative arepreferably alphaand beta-alkanediols containing from 2 to 18 carbonatoms. Such glycols include, for example, ethylene glycol, 1,2- and1,3-propanediol, 1,3-pentanediol, 2,3-butanediol, 1,2-hexanediol,2-methyl- 1,3-pentanediol, 1,2- and 1,3-octylene glycols including2-ethylhexane-l,3-diol, 1,2-dodecanediol, 2,4- diethyloctane-l,3-diol,and 2,4,6-triethyl-decane-l,3-diol. The glycols containing from 6 to 10carbon atoms are more preferred since they impart an optimum degree ofoil solubility to the titanate. Alphaand beta-octylene glycols such as2-ethylheXane-1,3-diol have been found to be the most satisfactory forpresent purposes since they give unusually effective oxidation andcorrosion inhibitors.

The polyhydroxy benzenes are preferably vicinal dihydric phenols such ascatechol, 3,4-dihydroxy toluene, tert.-butylcatechol, cetylcatechol, andthe like. They may contain additional hydroxyl groups, as for example,1,2,4- trihydroxy benzene. Alkyl catechols containing from 2 to 18carbon atoms in the alkyl group are at present most preferred since thetitanates prepared from them possess the most satisfactoryoil-solubility characteristics.

Suitable reactive titanic acid derivatives, as illustrate invention.eating oils of naphthenic, parafiinic, and mixed naphsuitable.

be prepared by heating a mixture of the complex of titanic acid withglycol or polyhydroxy benzene and an organic amine such as trimethylamine, triethanol amine,lauryl amine, phenyl-alpha-naphthylamine, aminophenol, pyridine, etc. The esters may be prepared by reacting thetitanium tetrahalide at the beginning with aliphatic alcohols andglycols such as ethyl alcohol, butyl alcohol, 2-ethylhexanediol-l,3,pentaerythritol, cetyl alcohol, etc.

The complex of titanic acid with glycol or polyhydroxy benzene ispresent in the compositions of the invention in an amount at leastsufficient to inhibit corrosion .orv oxidation. Small amounts, usuallyfrom about 0.01 to about 5.0 percent by weight based on the oil, areeffective. Proportions ranging from about 0.05 to about 1.0 percent arepreferred in most lubricating oil compositions. Concentrates containinglarger proportions, up to '50 percent, either in solution or suspension,are particularly suitable in compounding operations.

Any of the well-known types of oils of lubricating viscosity aresuitable base oils for the compositions of the They include hydrocarbonor mineral lubritheme and paratfinic types. They may be refined by anyof the conventional methods such as solvent refining and acid refining.Synthetic hydrocarbon oils of the a-lkylene polymer type or thosederived from coal and shale may also be employed. Alkylene oxidepolymers and their derivatives such as the propylene oxide polymers and'their ethyl esters and acetyl derivatives in which the terminal hydroxylgroups have been modified are also Synthetic oils of the dicarboxylicacid ester type including dibutyl adipate, di-Z-ethylhexyl seba'cate,di-n-hexyl fumaric polymer, dilauryl azelatc, and the like may be used.Alkyl benzene types of synthetic oils such as tetradecyl benzene, etc.are also included. Liquid esters of acids of phosphorus includingtricresyl phosphate, diethyl esters of decane phosphonic acid, and thelike may also be employed. Also suitable are the polysiloxane oils ofthe type of polyalkyl, polyaryl, polyalkoxy and polyaryloxy siloxanessuch as polymethyl siloxane, polymethylphenyl siloxane andpolymethoxyphenoxy siloxane and silicate ester oils such as tetraalkyland tetraaryl silicates of the tetra-2-ethylhexyl silicate andtetrap-tert.-butylphenyl silicate types.

In a preferred embodiment of the invention, as mentioned above, thecomplexes of titanic acid with glycol or polyhydroxy benzene areemployed in combination with compounded mineral lubricating oils of theinternal combustion engine type which are normally corrosive to alloybearings. In such an embodiment, as in the case of the other, straightoils of lubricating viscosity, a major proportion of the lubricating oilnormally corrosive to metals and/or subject to oxidation and a smallamount, suflicient :0 inhibit said corrosion and/or oxidation, of atitanic acid complex provides a remarkably improved composi- Lion. Thesecompounded oils customarily contain deergents such as the oil-solublepetroleum sulfonates and itabilizers such as the metal alkyl phenates.Other tgCIltS such'as oiliness agents, viscosity index improvers, :ourpoint depressants, blooming agents, peptizing agents, to. may also bepresent. 1

In further illustration of the invention, the following :xamples aresubmitted showing" the preparation of the itanic acid complexes andevaluation of their effectivea'reasss W EXAMPLE 1 Into a reaction flaskequipped with a mechanical stirrer and vented through a calcium chloridedrying tube are placed 148 grams of anhydrous butyl alcohol and 850milliliters of toluene. The flask is immersed in an ice bath. When thetemperature of the contents reaches 10 C., 1.90 grams of titaniumtetrachloride are added dropwise at a rate so the temperature ismaintained between 10 C. and 15 C. Stirring is continued for 2 hoursWhile nitrogen gas is bubbled through the reaction mixture to removehydrogen chloride. When the reaction is complete, which is indicated byhydrogen chloride no longer being evolved, the toluene solvent isremoved by vacuum distillation at 1 mm. Hg pressure leaving the dibutyldichlorotitanate reaction product.

The dibutyl dichlorotitanate obtained above is added to 292 gramsof2-ethylhexanediol-1,3 in a reaction flask. 180 grams of pyridine areadded to take up the hydrogen chloride formed and the mixture is warmedslightly to accelerate the reaction. When the reaction is complete, thesolid pyridine hydrochloride is separated from the liquid portion of thereaction mixture. The pyridine hydrochloride is washed with severalportions of anhydrous toluene which are collected and added to theliquid reaction mixture. The combined liquid portions are then vacuumdistilled at a pressure of 1 mm. Hg to remove the toluene and excess2-ethylhexanediol-1,3 leaving the dibutyl ester ofdi(2-ethylhexanediol-l,3) titanate as a clear, light yellow, highlyviscous, tacky product which is insoluble in water, soluble in ethylalcohol and very soluble in hydrocarbon solvent.

EXAMPLE 2 Approximately 500 grams of dibutyl ester of di(2-ethylhexanediol-l,3) titanate of the type illustrated in the aboveexample are combined with about 50 grams of water. The mixture isagitated with a mechanical stirring arrangement. The butyl alcoholproduced by hydrolysis is removed from the mixture by vacuumdistillation at 1 mm. Hg pressure and amounts to approximately 150 gramswhich corresponds closely to theoretical. The di(2-ethylhexanediol-1,3)titanate is separated from the aqueous mixture obtained above bydecanting the supernatent water. It is a light yellow, tacky, semisolidclosely similar to the dibutyl ester of di(2-ethylhexanediol-1,3)'titanate of the preceding illustration,

The efiectiveness of the lubricating oil compositions of the inventionis demonstrated by the copper-lead strip corrosiontest. In thistest apolished copper-lead strip is weighed and immersed in 300 cubiccentimeters of test oil in a 400-milli1iter lipless Berzelius beaker.The test oil is maintained at 340 F..under a pressure of one atmosphereof oxygen, and stirred with a mechanical stirrer at 1,000

'R. P. M. After two hours a synthetic naphthenate catalyst is added,unless otherwise specified, to provide the following catalytic metals:

Percent by weight Iron 0.008 Lead 0.004, Copper 0.002 Manganese 0.0005Chromium 0.004

The test is continued. 20 hours. The copper-lead strip is then removed,rubbed vigorously with a soft cloth and mineral oil and a compoundedmineral lubricatingoil corrosive to alloy bearings. .vent 'refined-SAE40 mineral lubricating oil base having a of the internal combustionengine type which is normally The compounded oil isa solviscosity indexof 60 and containing 10 mM/kg. of neutral calcium petroleum sulfonateand 20 mM/kg. of calcium alkyl phenate, sulfurized. The results of thetest are shown in the following table. The concentrations of titanicacid complex employed are given in either millimoles of titanium perkilogram of oil or percent by weight of the composition.

Table I COPPER-LEAD STRIP CORROSION TEST Copper- Lea Additive Base OilStrip Weight Loss e None Mineral lub. oil 105, 4.0%di(2-ethylhexanediol-1,3) titanate Same .r 79.0 None Oompounded oi1 302.0 0.6% dibutyl ester of di(2-ethylhexanedi- Same 8. 2

01-1, titanate. 0.3% dibutyl ester of di(2-ethylhexane-' 56.4

d1ol-1,3).titanate. 0.5% di(2-ethylhexanediol-1,3) titanate 41. 0 1.0%dl(2-ethy1l1exanediol-l,3) titanate l4. 7 0.6% monobutyltri(2-ethylhexanediol- 14.0

1,3) titanate.

As shown by the above test data, straight mineral lubricating oil alonegives a copper-lead strip weight loss due to corrosion of over 105milligrams in the 20-hour period. By way of distinction, compositions inaccordance with this invention containing the same straight minerallubricating oil base and a titanate corrosion inhibitor give as littleas 79 milligrams weight loss. In the case of the conventional compoundedmineral lubricating oils of the internal combustion engine type whichare normally corrosive to copper-lead bearings, the improvement is evenmore remarkable. The compounded oil alone gives copperlead strip weightlosses ranging as high as 300 milligrams whereas the lubricating oilcompositions of the invention containing the same compounded base oilplus a glycol fomplex of titanic acid result in very little or nocorrosion oss.

The lubricating oil compositions illustrative of the invention are alsoevaluated for their efiectiveness as inhibitors in gasoline typeinternal combustion engines. This test is termed the L-4 Strip CorrosionTest because of its correlation with the L-4 Chevrolet Engine Testreferred to in the C. R. C. Handbook, 1946 edition, CoordinatingResearch Council, New York, New York. In the test the same apparatus andconditions as described in the above copper-lead strip corrosion testare employed with two essential modifications. The temperature ismaintained at 295 F. to simulate lower temperatures encountered ingasoline engines and a synthetic naphthenate catalyst of the followingtype is used containing lead in further duplication of gasoline engineoperation:

Percent by weight Copper 0.0095 Iron 0.0056 Manganese 0.0005 Lead -i0.11 Tin 0.0049

The reference oil is a compounded oil consisting of a solvent refined140 neutral mineral lubricating oil base containing 3.75% by weightbased on the composition of a polymethacrylate glycol ester ashlessdetergent.

The nature of the improved lubricating oil compositions of the inventionand their effectiveness should be readily apparent from the manyillustrations given above. Oxidation and corrosivity in the compositionsare definitely inhibited to a very substantial degree. Particularlycorrodible metals such as engine alloy bearings of copper, lead, and thelike, as well as bearings of silver, are not adversely afiected. This isindeed remarkable since the problem of devising lubricant compositionsuniformly noncorrosive to both types of bearing metals has longconfronted workers in the art. The advantagesof these improvements areobtained without loss of other desirable properties of the lubricantcompositions.

As mentioned above, the titanium compounds of the compositions accordingto this invention are preferably formed from titanic acid, etc. and analphaor beta-diol or vicinal dihydroxy benzene. Although the presentinvention is in no way limited to any theory concerning the structure ofthe compounds, it is believed that they may be illustrated by thefollowing formulae:

Diglycol titanates OH 1\O/ Di-pyrocatechol tltana'tes wherein R ishydrogen or a group of hydrocarbon structures as previously described.

Although the above types of compounds are distinctly preferred in thecompositions of the invention, other compounds of similar structurehaving substituents on the hydrocarbon groups which do not adverselyaffect the reaction may likewise be employed. Such substituents include:hydroxyl groups, as when a polyhydroxy alcohol or benzene such asglycerol, pentaerythritol, sorbitol or trihydroxy benzene is used; estergroups, as when glycerol monooleate or sorbitan monooleate is used; andhalogens, others, amides, etc., as will be apparent to those skilled inthe art from the above description of the invention.

Although the compositions of the invention have been primarily describedas crankcase lubricants for internal combustion engines, they are alsouseful as turbine oils, hydraulic fluids, instrument oils, constituentoils in grease manufacture, ice-machine oils, and the like.

I claim:

1. A lubricant composition comprising an oil of lubricating viscosityand a member of the group consisting of titanates of .alphaandbeta-glycols" of 6 'to-10'carb'on atoms in an amount sufficient toinhibit corrosion.

'2. 'A' lubricant composition comprising anoil of lubricating viscosityand 0.01 to 5.0 percent by weight based on the oil of a titanate of2-ethylheXane-L3-sdio1.

' 3.. A lubricant composition comprising a mineral lubricating oil forinternal combustion engines which is normally corrosive to alloybearings anda member of the group consisting of titanate of alphaandbeta-glycols of 6 to 10 carbon atoms in an amount sufficient to inhibitcorrosion.

4. A lubricant composition comprising a mineral lubricating oil forinternal combustion engineswhich is normazlly corrosive to alloybearings and a titanate of an alpha-alkanediol containing from 6 to 10carbon atoms in an amount sufficient to inhibit corrosion.

5. A lubricant composition comprising a mineral lubrieating oil forinternal combustion engines which is normally corrosive to alloybearings and a titanate of a betaalkanediol containing from 6 to 10carbon atoms in an amount suflicient to inhibit corrosion.

6. A lubricant composition comprising a mineral lubrieating oil forinternal combustion engines which is normally corrosive to alloybearings and from about 0.01 to about 5.0 percent by weight based on theoil of a titanate of 2-ethylhexane-1,3-diol. r

7. A lubricant composition comprising a mineral lubricating oil forinternal,combustionfengines'which is normally corrosive to alloybearings and from about'0.01 to to about 5.0 percent by weight based onthe oil of dibutyl ester of di(2-ethylheXanedio1-l,3) titanate.

8. A lubricant composition comprising a mineral lubricating oil forinternal combustion engines which is normally corrosive to alloybearings and from about 0.01 to about 5.0 percent by weight based on theoil of K1i(2-ethy1 hexane:diol-1,3) titanate.

References Cited in the file of this patent UNITED STATES PATENTS SwissMar. 22, 1949

1. A LUBRICANT COMPOSITION COMPRISING AN OIL OF LUBRICATING VISCOSITYAND A MEMBER OF THE GROUP CONSISTING OF TITANATES OF ALPHA- ANDBETA-GLYCOLS OF 6 TO 10 CARBON ATOMS IN AN AMOUNT SUFFICIENT TO INHIBITCORROSION.